We went in Sept. 2012 with DD3 who loved Legos, but was somewhat timid.
The drive wasn't bad at all. We stopped for lunch on the way over at McDonald's just outside Winterhaven.
We found that
Legoland was much less magical, but still fun. DD was able to ride the majority of the rides and enjoyed the ones she tried. My husband loved the miniature
Lego city area and all of the models.
We all loved the portion that was dedicated the Cyprus Gardens. It was gorgeous. Since the waterpark won't be open in November, you'll be able to accomplish a lot. The longest line that we stood in was <10 minutes.
That said, we don't feel the need to go back. We bought some tickets online from an organization that was doing a fundraiser. We got all of our tickets for $25 a piece. My husband and I agreed that if we'd paid full price (even with a free child's ticket), we'd have been very disappointed.
You should also note that the store at the park is not an official Lego Store and you cannot use (nor earn, if I remember correctly) VIP points. So, if you want vacation Legos, get them at DTD.